| 摘要 |
1,135,558. Semi-conductor devices. RADIO CORPORATION OF AMERICA. 18 April, 1966 [26 April, 1965], No. 16825/66. Heading H1K. In a transistor having a low collector capacitance, a limited portion 36 of the collector region adjacent to the base region 38 and lying directly below the emitter region 40 is of lower resistivity than the remainder 14b of the collector region, Fig. 9. A plurality of transistors are produced by growing an N-type silicon epitaxial layer (14) on an N+type substrate (10), Fig. 2 (not shown), thermally growing an oxide layer (18), Fig. 3 (not shown), etching windows (22), (24) in oxide layer (18) and vapour depositing layers (26) of antimony on to the exposed surfaces, Fig. 4 (not shown). A second oxide layer (28) is then grown, the oxide growing faster in the windows than over the remainder of the surface so that the thickness of the epitaxial layer (14) is reduced at these points, Fig. 5 (not shown). The oxide layers (18), (28) are removed by etching, exposing depressions (30), Fig. 6 (not shown), and a second N-type epitaxial layer (14a) is grown, depressions (30a) being formed in its surface above the previous depressions (30), Fig. 7 (not shown). The wafer is then heated to diffuse the antimony layers (26) into the epitaxial layers (14), (14a) to form the low resistivity portion (36) of the collector region (14b), Fig. 8 (not shown). P-type base region 38 and N-type emitter region 40 are then diffused into the wafer, the emitter region being located directly above region 36 by means of the depression 30a. Base and emitter leads may be connected by means of evaporated metal layers and substrate 10 may form the collector contact. The semi-conductor material may also be germanium. |
